Question

Pinworm: USE SOFTWARE In a prior sample of U.S. adults, the Center for Disease Control (CDC), found that 8% of the people in this sample had pinworm but the margin of error for the population estimate was too large. They want an estimate that is in error by no more than 2.5 percentage points at the 90% confidence level. Enter your answers as whole numbers.

(a) What is the minimum sample size required to obtain this type of accuracy? Use the prior sample proportion in your calculation.

The minimum sample size is U.S. adults.

(b) What is the minimum sample size required to obtain this type of accuracy when you assume no prior knowledge of the sample proportion?

The minimum sample size is U.S. adults.

Answer 1

Given that, margin of error ( E ) = 2.5% = 0.025

A 90% confidence level has significance level of 0.10 and critical value is,

We want to find, the sample size for the following cases,

a) prior sample proportion = p = 0.08

Therefore, required sample size is 319

b) If no prior sample proportion is given, so assume p = 0.5

Therefore, required sample size is 1082

Note: If you want sample size is to next whole number then n = 1083 and required sample size is 1083.